Anesthesia and analgesia
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We accomplished endotracheal intubation by using fluoroscopic direction in a patient presenting a difficult airway both on the basis of a preanesthetic physical examination and on the basis of a potential for cervical cord injury associated with complicated laryngoscopy. Under topical anesthesia, a multipurpose angiographic (MPA) catheter over a Bentson wire was advanced into the trachea under intermittent C-arm fluoroscopic guidance while the occiput, cervical spine, and mandible remained in a neutral position. The endotracheal tube was then easily advanced over the MPA catheter into the trachea, where the location was documented by fluoroscopic view. Because of judicious use of topical anesthesia and the small diameter and flexibility of the MPA catheter, the unsedated patient remained comfortable throughout the procedure. The stored data were later transferred to a compact disk, and a copy was provided to the patient as an adjunct to Medic-Alert. Unlike fiberoscopy, with which the view can be totally obscured by secretions, blood, and abnormal anatomy, the direction and location of the MPA catheter within the airway were easily identifiable throughout the procedure. The small diameter of the MPA (1.5-mm outer diameter) should allow placement of endotracheal tubes as small as 3.0-mm inner diameter--an option not available even with pediatric instruments. Although time was not a consideration, the procedure was accomplished in <12 min with 22 s of fluoroscopy. We believe that with experience, atraumatic intubation of a difficult airway could be accomplished routinely in less than 2 min with radiological-assisted intubation. ⋯ Radiologic-assisted intubation facilitated endotracheal intubation without sedation, instrumentation, or significant movement of the occiput, cervical spine, or mandible. The procedure was accomplished in <12 min and with only 22 s of fluoroscopy. This approach provides the ultimate adjunct to the preoperative airway physical evaluation while providing for immediate (or delayed) atraumatic endotracheal intubation. The diagnostic information and procedure can be recorded on a compact disk.
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Anesthesia and analgesia · May 2004
A survey of orthopedic surgeons' attitudes and knowledge regarding regional anesthesia.
We conducted a survey to explore the surgical attitudes and preferences regarding regional anesthesia among Canadian orthopedic surgeons. Surveys were returned by 468 (61%) of 768 surgeons. Forty-eight percent of respondents directed their patients' choice of anesthetic. Forty percent of surgeons directed their patients to choose regional anesthesia. The principal reasons for favoring regional anesthesia were less postoperative pain (32%), decreased nausea and vomiting (12%), and safety (14%). Reasons for not favoring regional anesthesia were delays in the induction of anesthesia (43%) and an unpredictable success rate (12%). This survey suggests that orthopedic surgeons are supportive of regional anesthesia. Barriers to increased popularity include perceived delays and unreliability. ⋯ Orthopedic surgeons understand the benefits of and are supportive of the use of regional anesthesia in their practices. Barriers to increased popularity include perceived operating room delays and lack of reliability.
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Anesthesia and analgesia · May 2004
Spinal anesthesia with bupivacaine decreases cerebral blood flow in former preterm infants.
Spinal anesthesia is commonly used in former preterm infants (FPI). In these patients, hypotension induced by spinal anesthesia may impair cerebral blood flow. We measured cerebral blood flow velocity (CBFV) by transcranial Doppler ultrasound to assess the effect of hypotension induced by spinal anesthesia on cerebral hemodynamics. Twelve FPI scheduled for inguinal hernia repair were operated under spinal anesthesia using 1 mg/kg isobaric 0.5% bupivacaine. Systolic, diastolic, and mean middle cerebral artery CBFV were measured at 5 min before and 5 min and 10 min after spinal anesthesia using a transcranial pulsed Doppler ultrasonography. Arterial blood pressure and heart rate were recorded simultaneously. Cerebral arteries resistance index (RI) was calculated as RI = (peak systolic CBFV - end-diastolic CBFV)/peak systolic CBFV. Diastolic CBFV decreased significantly from 30.0 +/- 11.1 cm/s to 20.1 +/- 8.4 cm/s at 5 min and to 20.1 +/- 7.0 cm/s at 10 min. RI increased significantly from 0.7 +/- 0.1 to 0.8 +/- 0.1 at 5 min and 10 min. Systolic, diastolic, and mean arterial blood pressures decreased significantly at the same time intervals. We suggest that in FPI, spinal anesthesia induces a decrease in cerebral blood flow related to changes in arterial blood pressure. Whether these changes have deleterious consequences remains to be determined. ⋯ In former preterm infants having spinal anesthesia with bupivacaine, a decrease in cerebral blood flow velocity is displayed by middle cerebral artery transcranial Doppler examination.
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Anesthesia and analgesia · May 2004
Case ReportsAnesthetic management of a patient in prone position with a drill bit penetrating the spinal canal at C1-C2, using a laryngeal mask.
Airway management in patients with penetrating neck trauma must guarantee cervical spine stability. Moreover, the prone position increases the risk of difficult ventilation and cervical spine injury. A 19-yr-old patient was brought to the emergency room in prone position with a drill bit protruding from the posterolateral aspect of his neck. The bit had entered the spinal canal below the first cervical vertebra, and placed near the odontoid peg. He was referred for surgical removal of the drill. The use of an inhaled induction of anesthesia, avoiding muscle relaxants, and ventilation through a laryngeal mask airway inserted in the prone position seemed to offer a satisfactory approach. ⋯ Management of patients with penetrating neck trauma must guarantee cervical spine stability. Moreover, the prone position increases the risk of difficult ventilation and cervical spine injury. Anesthesia may be induced and the airway can be managed with the patient already in the prone position for surgery.
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Anesthesia and analgesia · May 2004
The effects of isoflurane on desensitized wild-type and alpha 1(S270H) gamma-aminobutyric acid type A receptors.
gamma-aminobutyric acid type A receptors (GABA(A)-R) mediate synaptic inhibition and meet many pharmacological criteria required of important general anesthetic targets. During synaptic transmission GABA release is sufficient to saturate, maximally activate, and transiently desensitize postsynaptic GABA(A)-Rs. The resulting inhibitory postsynaptic currents (IPSCs) are prolonged by volatile anesthetics like isoflurane. We investigated the effects of isoflurane on maximally activated and desensitized GABA(A)-R currents expressed in Xenopus oocytes. Wild-type alpha(1)beta(2) and alpha(1)beta(2)gamma(2s) receptors were exposed to 600 microM GABA until currents reached a steady-state desensitized level. At clinical concentrations (0.02-0.3 mM), isoflurane produced a dose-dependent enhancement of steady-state desensitized current in alpha(1)beta(2) receptors, an effect that was less apparent in receptors including a gamma(2s)-subunit. When serine at position 270 is mutated to histidine (alpha(1)(S270H)) in the second transmembrane segment of the alpha(1)-subunit, the currents evoked by sub-saturating concentrations of GABA became less sensitive to isoflurane enhancement. In addition, isoflurane enhancements of desensitized currents were greatly attenuated by this mutation and were undetectable in alpha(1)(S270H)beta(2)gamma(2s) receptors. In conclusion, isoflurane enhancement of GABA(A)-R currents evoked by saturating concentrations of agonist is subunit-dependent. The effects of isoflurane on desensitized receptors may be partly responsible for the prolongation of IPSCs during anesthesia. ⋯ Isoflurane enhances desensitized gamma-aminobutyric acid type A receptor (GABA(A)-R) currents, an effect that is subunit-dependent and attenuated by a mutation in an alpha(1)-subunit pore residue of the GABA(A)-R. As GABA release at inhibitory synapses is typically saturating, isoflurane modulation of desensitized receptors may be partly responsible for prolongation of inhibitory postsynaptic currents during anesthesia.